1. Field of the Invention
The invention concerns a magnetic resonance system of the type having components, that include a magnetic field generation unit for generation of a basic magnetic field, gradient coils for generation of a field gradient as well as a radio-frequency coil arrangement with a number of radio-frequency coils for transmission and reception of radio-frequency signals; the components being respectively activated according to a sequence via at least one digital module and at least one analog module; with the analog modules being arranged external to a control computer that controls the digital modules.
2. Description of the Prior Art
Modern magnetic resonance systems embody a number of components that must be activated in the course of a measurement procedure (in particular a sequence) while observing fixed temporal correlations. Among these components are, for example: a magnetic field generation unit for generation of a basic magnetic field; gradient coils for generation of a field gradient; and a radio-frequency coil arrangement with a number of radio-frequency coils for transmission and reception of radio-frequency signals. Since such components typically are operated in an analog manner but the activation proceeds in a digital manner, a digital module and an analog module are provided on the activation path to these components.
If one considers the exemplary case of the radio-frequency coil arrangement, differentiation is frequently made between transmission modules and reception modules. For example, an analog reception module comprises an electronic with which the received signal is initially demodulated. The signal is additionally converted by an A/D converter into a reception digital signal. The reception digital signal is digitally demodulated and processed further in the digital reception module. The signal of a frequency generation unit (usually an NCO (Numerically Controlled Oscillator)) as well as an intermediate frequency is required for this. Such reception modules can process, for example, a specific number of reception channels.
In order to have to adhere to the predetermined time plan that is important for the measurement method, each component must implement specific actions at a precisely determined time, a central control concept is used in which the digital modules are integrated into the control computer. With the system clock of the control computer, and possibly a local clock or a timestamp, synchronization and iso-synchronizationare established. The digital modules can then be fashioned, for example, as modules that can be connected to a bus within the control computer.
Given such centrally organized control systems, a future maximum expansion must be taken into account in the design since the capacities of the control computer are limited both spatially and in terms of capacity. This maximum expansion, however, cannot be exactly planned for all system functionalities (thus components) at the point of time of the design since the technical developments proceed rapidly.
Under-equipages or even bottlenecks thus frequently occur in conventional control systems when the expansion possibilities are not sufficient.
Some niche solutions are known to address this problem. For example, it has been proposed to utilize a clone concept at the excitation side with regard to the radio-frequency coil arrangement, with which clone concept the control computer is duplicated multiple times, and one of the control computers is configured as a master, the others as slaves. This solution is technically very complicated and uneconomical and concerns only a partial aspect of one component. Such an individual solution is also known for the reception side, for which a bus expansion separate from the control computer is proposed. Again, a complete and economical solution of the aforementioned problem is not achieved.